Data of various types is recorded on and accessed from optical disks. Common optical disks include compact disks (CDs), CD-ROMs, digital versatile disks (DVDs), digital video disks (also abbreviated DVDs), or other similar disks. Some optical disks, such as DVDs, may be either single-sided or dual-sided. With conventional optical disk changers, a dual-sided optical disk must be manually “flipped” between sides in order to read data from both sides of the disk.
Three general types of optical disk changers capable of storing and reading multiple disks are known. In the first type, a number of disks are positioned coplanar to one another and radially about a center rotation point on a carrousel. To read any one disk, the carrousel is rotated until the desired disk is positioned adjacent to the disk reader. To read another disk, the present disk is disengaged from the reader and the carrousel is rotated to position another disk adjacent to the disk reader. However, such optical disk changers read only one side of a disk. Thus, operator intervention is required to flip the disk to allow the disk reader to read the opposite side of the disk.
The second type of multiple disk changer stores optical disks radially about a center rotation point on a carrousel, but with the rotational axis of each optical disk perpendicular to the axis of rotation of the carrousel. The resulting geometry of the plurality of stored disks is a toroid or “donut” shape. A disk from the carrousel is read by ejecting the disk from the carrousel into a disk reader.
The third type of multiple disk changer stores optical disks in a stack with the center of each disk coaxial with the centers of the other disks. A disk to be read is rotated or translated out from the stack and engaged by a disk reader. Just as with the first type of multiple disk changer, the changer can read only one side of a disk unless the disk is manually flipped by a user. Examples of this third type of multiple disk changer are illustrated in U.S. Pat. Nos. 4,807,208, 5,099,465, 5,153,862, 5,561,657, 5,682,364, and 5,692,878. However, these changers are only capable of reading one side of the optical disk unless the user manually flips the disk.
Therefore, although the prior art is capable of storing a large number of optical disks, the prior art does not provide an apparatus or method for reading both sides of a optical disk without manual operator intervention. Consequently, there is a need for an apparatus and method for automatically reading both sides of an optical disk by effectively flipping a dual-sided disk.